/*
 * @(#)GeneralBagFunction.java
 *
 * Copyright 2004-2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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package org.wso2.balana.cond;

import org.wso2.balana.ctx.EvaluationCtx;

import org.wso2.balana.attr.AttributeValue;
import org.wso2.balana.attr.BagAttribute;
import org.wso2.balana.attr.IntegerAttribute;

import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Specific <code>BagFunction</code> class that supports all of the
 * general-purpose bag functions: type-one-and-only, type-bag-size, and
 * type-bag.
 * 
 * @since 1.2
 * @author Seth Proctor
 */
public class GeneralBagFunction extends BagFunction {

	// private identifiers for the supported functions
	private static final int ID_BASE_ONE_AND_ONLY = 0;
	private static final int ID_BASE_BAG_SIZE = 1;
	private static final int ID_BASE_BAG = 2;

	// mapping of function name to its associated parameters
	private static HashMap paramMap;
	private static Set supportedIds;

	/**
	 * Static initializer that sets up the paramater info for all the supported
	 * functions.
	 */
	static {
		paramMap = new HashMap();

		for (int i = 0; i < baseTypes.length; i++) {
			String baseType = baseTypes[i];
			String functionBaseName = FUNCTION_NS + simpleTypes[i];

			paramMap.put(functionBaseName + NAME_BASE_ONE_AND_ONLY,
					new BagParameters(ID_BASE_ONE_AND_ONLY, baseType, true, 1,
							baseType, false));

			paramMap.put(functionBaseName + NAME_BASE_BAG_SIZE,
					new BagParameters(ID_BASE_BAG_SIZE, baseType, true, 1,
							IntegerAttribute.identifier, false));

			paramMap.put(functionBaseName + NAME_BASE_BAG, new BagParameters(
					ID_BASE_BAG, baseType, false, -1, baseType, true));
		}

		for (int i = 0; i < baseTypes2.length; i++) {
			String baseType = baseTypes2[i];
			String functionBaseName = FUNCTION_NS_2 + simpleTypes2[i];

			paramMap.put(functionBaseName + NAME_BASE_ONE_AND_ONLY,
					new BagParameters(ID_BASE_ONE_AND_ONLY, baseType, true, 1,
							baseType, false));

			paramMap.put(functionBaseName + NAME_BASE_BAG_SIZE,
					new BagParameters(ID_BASE_BAG_SIZE, baseType, true, 1,
							IntegerAttribute.identifier, false));

			paramMap.put(functionBaseName + NAME_BASE_BAG, new BagParameters(
					ID_BASE_BAG, baseType, false, -1, baseType, true));
		}

		supportedIds = Collections.unmodifiableSet(new HashSet(paramMap
				.keySet()));

		paramMap.put(NAME_BASE_ONE_AND_ONLY, new BagParameters(
				ID_BASE_ONE_AND_ONLY, null, true, 1, null, false));
		paramMap.put(NAME_BASE_BAG_SIZE, new BagParameters(ID_BASE_BAG_SIZE,
				null, true, 1, IntegerAttribute.identifier, false));
		paramMap.put(NAME_BASE_BAG, new BagParameters(ID_BASE_BAG, null, false,
				-1, null, true));

	};

	/**
	 * Constructor that is used to create one of the general-purpose standard
	 * bag functions. The name supplied must be one of the standard XACML
	 * functions supported by this class, including the full namespace,
	 * otherwise an exception is thrown. Look in <code>BagFunction</code> for
	 * details about the supported names.
	 * 
	 * @param functionName
	 *            the name of the function to create
	 * 
	 * @throws IllegalArgumentException
	 *             if the function is unknown
	 */
	public GeneralBagFunction(String functionName) {
		super(functionName, getId(functionName), getArgumentType(functionName),
				getIsBag(functionName), getNumArgs(functionName),
				getReturnType(functionName), getReturnsBag(functionName));
	}

	/**
	 * Constructor that is used to create instances of general-purpose bag
	 * functions for new (non-standard) datatypes. This is equivalent to using
	 * the <code>getInstance</code> methods in <code>BagFunction</code> and is
	 * generally only used by the run-time configuration code.
	 * 
	 * @param functionName
	 *            the name of the new function
	 * @param datatype
	 *            the full identifier for the supported datatype
	 * @param functionType
	 *            which kind of Bag function, based on the
	 *            <code>NAME_BASE_*</code> fields
	 */
	public GeneralBagFunction(String functionName, String datatype,
			String functionType) {
		super(functionName, getId(functionType), datatype,
				getIsBag(functionType), getNumArgs(functionType),
				getCustomReturnType(functionType, datatype),
				getReturnsBag(functionType));
	}

	/**
	 * Private helper that returns the internal identifier used for the given
	 * standard function.
	 */
	private static int getId(String functionName) {
		BagParameters params = (BagParameters) (paramMap.get(functionName));

		if (params == null)
			throw new IllegalArgumentException("unknown bag function: "
					+ functionName);

		return params.id;
	}

	/**
	 * Private helper that returns the argument type for the given standard
	 * function. Note that this doesn't check on the return value since the
	 * method always is called after getId, so we assume that the function is
	 * present.
	 */
	private static String getArgumentType(String functionName) {
		return ((BagParameters) (paramMap.get(functionName))).arg;
	}

	/**
	 * Private helper that returns if the given standard function takes a bag.
	 * Note that this doesn't check on the return value since the method always
	 * is called after getId, so we assume that the function is present.
	 */
	private static boolean getIsBag(String functionName) {
		return ((BagParameters) (paramMap.get(functionName))).argIsBag;
	}

	/**
	 * Private helper that returns the argument count for the given standard
	 * function. Note that this doesn't check on the return value since the
	 * method always is called after getId, so we assume that the function is
	 * present.
	 */
	private static int getNumArgs(String functionName) {
		return ((BagParameters) (paramMap.get(functionName))).params;
	}

	/**
	 * Private helper that returns the return type for the given standard
	 * function. Note that this doesn't check on the return value since the
	 * method always is called after getId, so we assume that the function is
	 * present.
	 */
	private static String getReturnType(String functionName) {
		return ((BagParameters) (paramMap.get(functionName))).returnType;
	}

	/**
	 * Private helper that returns if the return type is a bag for the given
	 * standard function. Note that this doesn't check on the return value since
	 * the method always is called after getId, so we assume that the function
	 * is present.
	 */
	private static boolean getReturnsBag(String functionName) {
		return ((BagParameters) (paramMap.get(functionName))).returnsBag;
	}

	/**
	 * Private helper used by the custom datatype constructor to figure out what
	 * the return type is. Note that this doesn't check on the return value
	 * since the method always is called after getId, so we assume that the
	 * function is present.
	 */
	private static String getCustomReturnType(String functionType,
			String datatype) {
		String ret = ((BagParameters) (paramMap.get(functionType))).returnType;

		if (ret == null)
			return datatype;
		else
			return ret;
	}

	/**
	 * Returns a <code>Set</code> containing all the function identifiers
	 * supported by this class.
	 * 
	 * @return a <code>Set</code> of <code>String</code>s
	 */
	public static Set getSupportedIdentifiers() {
		return supportedIds;
	}

	/**
	 * Evaluate the function, using the specified parameters.
	 * 
	 * @param inputs
	 *            a <code>List</code> of <code>Evaluatable</code> objects
	 *            representing the arguments passed to the function
	 * @param context
	 *            an <code>EvaluationCtx</code> so that the
	 *            <code>Evaluatable</code> objects can be evaluated
	 * @return an <code>EvaluationResult</code> representing the function's
	 *         result
	 */
	public EvaluationResult evaluate(List inputs, EvaluationCtx context) {

		// Evaluate the arguments
		AttributeValue[] argValues = new AttributeValue[inputs.size()];
		EvaluationResult result = evalArgs(inputs, context, argValues);
		if (result != null)
			return result;

		// Now that we have real values, perform the requested operation.
		AttributeValue attrResult = null;

		switch (getFunctionId()) {

		// *-one-and-only takes a single bag and returns a
		// single value of baseType
		case ID_BASE_ONE_AND_ONLY: {
			BagAttribute bag = (BagAttribute) (argValues[0]);

			if (bag.size() != 1)
				return makeProcessingError(getFunctionName() + " expects "
						+ "a bag that contains a single "
						+ "element, got a bag with " + bag.size() + " elements");

			attrResult = (AttributeValue) (bag.iterator().next());
			break;
		}

		// *-size takes a single bag and returns an integer
		case ID_BASE_BAG_SIZE: {
			BagAttribute bag = (BagAttribute) (argValues[0]);

			attrResult = new IntegerAttribute(bag.size());
			break;
		}

		// *-bag takes any number of elements of baseType and
		// returns a bag containing those elements
		case ID_BASE_BAG: {
			List argsList = Arrays.asList(argValues);

			attrResult = new BagAttribute(getReturnType(), argsList);
			break;
		}
		}

		return new EvaluationResult(attrResult);
	}

	/**
	 * Private class that is used for mapping each function to it set of
	 * parameters.
	 */
	private static class BagParameters {
		public int id;
		public String arg;
		public boolean argIsBag;
		public int params;
		public String returnType;
		public boolean returnsBag;

		public BagParameters(int id, String arg, boolean argIsBag, int params,
				String returnType, boolean returnsBag) {
			this.id = id;
			this.arg = arg;
			this.argIsBag = argIsBag;
			this.params = params;
			this.returnType = returnType;
			this.returnsBag = returnsBag;
		}
	}

}
